MAG5035

Still trying to gauge the degree of which the severe potential gets realized tomorrow. High res guidance seems to be tightening the window when the best shear coincides with the surge of some modest CAPE into the Sus Valley, more in the late morning/early afternoon. HRRR looked like it was toying around with some discrete and/or quasi linear convection during that timeframe, while the 3k NAM doesn’t have much at all until the frontal passage. FROPA looked slated for roughly the 4-8pm timeframe west to east in C-PA. Discrete development out ahead depends on if there’s any kind of ample daytime heating via some breaks in the clouds, something I’m not quite sure happens in earnest in PA. Line with the FROPA will be more purely dynamics driven, but we’ll have to see how well it gets organized Also lost in all the attention to the severe is energy rounding the base of the trough during tomorrow generating a secondary wave of heavier precip riding up behind the front. So suddenly it looks quite snowy in at least the western half of PA early to mid Mon evening. This could drive a changeover to a period of snow all the way into the Sus Valley. Given the broad model support I’d be surprised if CTP didn’t at least headline the Laurels and north central Alleghenies for advisories. There’s support for the I-99 corridor as well. That will also be interesting to watch evolve tomorrow in addition to the severe threat. GFS vs Euro 3k NAM vs RGEM

The May 31st, 1985 tornado outbreak was more severe and remarkable than 1998 or any other more recent PA involved outbreak by a pretty sizeable margin. That outbreak spun up 43 tornadoes and killed 89 people (1000 injured) in PA, NY, OH and Ontario (65 alone in PA), produced PA’s only ever EF5 tornado (Wheatland), and also produced what I’m pretty sure was one of the widest tornadoes ever recorded in the US at the time (Moshannon State Forest). Couple screen grabs below but there’s some really informative links about this outbreak CTP’s 35th anniversary link- https://www.weather.gov/ctp/TornadoOutbreak_may311985 New interactive link they made for the 40th anniversary last year collaborated with NWS Pittsburgh, State College, Buffalo, and Cleveland https://storymaps.arcgis.com/stories/e8c12f670d5648a9b64877f42660eeeb

Count me in on this thinking as well, in PA at least. Certainly dynamics look very favorable in terms of shear/helicity, along with very high low level winds to tap down. Whether or not south-central/Sus Valley cracks all the way into the warm sector ahead of the front to take fuller advantage of those dynamics seems to be a main potential limiting factor. 18z 3k NAM never really builds much CAPE in the Sus Valley (cloud cover), having a narrow corridor of modest CAPE further west in the south-central counties. Newest high res model runs doesn’t look particularly organized with any kind of solid QLCS line, which would be the primary threat here over discrete cells… though I wouldn’t rule those out completely, esp with any breaks to help with daytime heating. As a side note the 18z 3k NAM was a prolific snow maker behind the front in western/central PA and other high res like the HRRR has at least a couple inches mainly in the Laurels/north-central. As another side note, this is occurring tomorrow literally one year to the date last year that we had a QLCS type line come through mainly the western and central part of the state with many tornado warnings and an 89mph wind gust at Latrobe.

I was just playing around with the archived radar data that’s on RadarScope Pro the other day. Here’s that tornado, that’s a pretty pronounced velocity couplet for 1998 NEXRAD data. It was roughly reading 110-115mph gate to gate on the data.

Yea sorry about that haha, I was exploring how far back the archived radar data went, that’s from 3/13/93. .

Here’s an archived radar image I could get on board with. Some other March 13th a while back.

When I ponied up and upgraded my RadarScope to the Pro subscription this winter I forgot one of the features was archived radar data. So this is a really good example to try it out and review something. Basically, I’m not doubting the chances that this storm might have spun something weak up somewhere along the way but I think this posted screengrab of the CC labeled as a debris ball to prove a tornado on the ground is a bit of a stretch. So here’s the 606pm image that was shared, crosshairs placed on the “debris ball” One thing about debris ball signatures is the area of low CC values are usually co-located to an area of high DBZ reflectivity values, which this CC signature is not. They’re also typically associated with established, strong tornadoes (>EF2), which I’m not really seeing the support for on velocity data, or obs/local storm reports. Even though this passed thru a relatively sparse area, it did still cross US 22/322 during this period. There weren’t very many reports on this storm at all looking over the LSR’s. This signature likely had more to do with the hail core that this cell did have with it, which will reduce the CC values and can also cause a corridor of reduced values in the downstream direction of the radar beam when there’s a pretty decent hail core.. which can be seen on the images.

That’s just crazy how that all evolved down there this morning. The DCA ob was even registering a heat index last night when I had posted about it. People in there rating/upgrading their winters to A’s and such haha. If I don’t get any more snow this season beyond like a 1-2” bush bender I’m rating my winter a C-, and it’ll take a late March/early April 2018 type run for me to rate it any better than a C+. The only reason I won’t rate it worse than a C is the consistent cold + scoring the big storm on 1/25. But temps were similarly cold consistently last winter too, just without the big storm. My snow total is sitting basically on par with the last 4 winters, which were all solidly below normal for here. So I’m grading tough.

I know this isn’t our area but it’s going on midnight and it’s still nearly 80ºF in and around DC, on March 11th. That’s nuts

Here’s the follow up on all this haha

Busted back out of the overcast/drizzle this afternoon and well into the 60s again today (as high ans 65ºF) after it had moved back in after dark last night. The severe setup definitely escalated quickly in western PA, with temps reaching near 80 with dewpoints near 60. Decent shear/wind parameters and at least some CAPE (500-1000) along with some discrete cell formation. That will definitely need monitored over there. Obviously will remain much more stable in eastern PA at the low levels with the overcast and cool air damming but might still be some rumbles of thunder with anything that makes it over that way tonight. I do expect non-diurnal warming this evening in the spots that have been most locked in to the CAD as the approaching system/ SW flow will eventually mix some of the warmth down.

I busted out of the clouds here, was as high as 63ºF earlier. Still around 61ºF

0.65” of rain here yesterday. Eastern PA definitely looks to be denied a full torch this weekend as cool air damming, cloud cover and maritime flow off the Atlantic have a firm hold east of the mountains. Meanwhile from the Laurels westward, increasing breezy southwest flow is going to make for much warmer temps, likely making a run at 65-70 or so on Saturday. Sus Valley may eventually mix down 50s to near 60 later Saturday/Sat night as a weak frontal passage approaches. Mon-Wed is the real time frame where it looks quite warm, as it has looked consistently on models for like the last week. Tuesday is the best chance for at least the southern half of PA to make a run at 70ºF ahead of the next system. Some difference between Euro and GFS with the Euro being much more expansive in PA with the very warm temps and GFS more confined to southern PA. Much more uncertainty abound beyond that, big differences between the Euro and GFS. Euro has been way colder around the St Patty’s day timeframe and also has a storm on tonight’s 0z run. GFS bottles up cold air more in Canada and runs a further north storm track. Both models and ensembles develop the really negative WPO, which should put a lot more cold back in Canada. They’re also pretty firm on a pretty positive AO and NAO though, which would suggest cold intrusions into the US are limited and brief. Difference area is the PNA, where the Euro/ensembles (and Canadian) reverses a pretty negative PNA to positive to set up western ridging and a chance at the kind of storm it puts out at 0z tonight and holding a cold pattern more. The GFS op just keeps the PNA solidly negative and its ensembles do reflect the other models more with the reversal but is more neutral. I’m fairly pessimistic overall on any decent snow chances in that timeframe mainly due to the +NAO/AO, but building a western ridge even briefly would at least allow for a window to try to line something up.

Freezing rain has arrived here and quickly glazing. 29/27ºF

BGM’s take, since they have been updating CTP’s AFD since yesterday morning.

This one’s for you @Voyagerhaha. Once we route out the lingering cold later next week after whatever happens Monday, guidance shifts high pressure to a Bermuda high positioning and that would likely usher in the warmest air we’ve seen since about October. Euro/GFS both have multiple days in the 70s late next week into next weekend. Given setup and teleconnections (+AO/NAO, +EPO, -PNA) I don’t think this one get’s muted.

The NBM looks quite good with it as well at the moment. Hopefully we don’t lose it like the system that originally looked like it was going to impact tomorrow or this thing edges north more and we end up with a messier outcome I do believe this potential event might be the last good shot at something decent for awhile as the signals for a more persistent and significant warm up in the East beginning later next week are looking pretty strong.

Probably the Horseshoe Curve, which would make sense given such high seasonal totals and also being that timeframe was Altoona’s Pennsylvania RR heyday where a lot of that kind of reporting was likely done along the mainline. That’s close to halfway up the Allegheny Front (leading ridge of the Laurels) between the city itself and the top at Gallitzin/Cresson. It’s hard to find much reliable data for the city itself. KAOO is more than 15 miles and one ridgeline over SE of the city. The airport doesn’t get as much snow, esp in upslope/LES and clipper situations being just that much further away from the Laurels with downsloping. Then of course, the really high variance from the city to the top of the Laurels in just a 5-10 mile drive. I consider roughly 40-50” an average season here, using the much more reliable snow data up in State College as a general baseline (45.9 since 1893 and 43.8 on the 1991-2020 avg). It’s not perfect but I am averaging 35.7” since the 17-18 winter with some pretty lousy winters the last 4 years. On the other hand, what will be the new 30 year avg (2001-2030) is currently running around 38” a season for State College right now barring some big winters the next 4 years.

I had a light coating first thing this morning but that is long gone as well as some of other snow that is on the ground. Despite getting the first double digit storm in 5 years and the prolonged cold and pack, I’d probably rate my winter a C if not much else happened next month. The only other snowfall that even got to the 3” mark this winter here was all the way back on Dec 2nd.

I’ve mentioned it somewhere in one of these threads in the past. I don’t believe that event dumped anywhere near that much snow in Harrisburg though. The NOAA NOWdata at Harrisburg/Middletown for those two days has over 3” of precip but only 2.4” of snow. It did dump those kinds of amounts back this way and on down the Apps thru WV and KY though. The local station here had something on it a few years ago. https://www.wtaj.com/weather/the-late-april-snowstorm-of-1928/

That makes me wonder about the statistical anomaly of the stretch of winters from 92-96 (sans 94/95), which in additional to being 3 of State College’s top 5 snowiest winters (93/94 #1 with 109.3”) was the heyday of really big snowstorms back this way. 12/10/92, 93 Superstorm, and the 3/3/94 nor’easter were three events in basically two winters that delivered that kind of snow in this part of central PA.

2.9” was what ended up calling the snow total here, about 1.3” from approx midnight to 8am Sunday morning and then another 1.6” from mid Sunday evening thru mid morning today. Some upslope stuff trying to set up so maybe can sneak a little bit more. This brings my season total to a fairly meh 28.7”, generally on par with the last 4 winters if winter ended today. Plenty of time obviously but it’s starting to get late. Clipper tomorrow night will likely favor NW PA, Laurels and perhaps down I-80 over to the Poconos. Track of the low staying in the lakes doesn’t bode well for much making it into the Sus Valley (downsloping). Then we’ll see what we have to work with for Thursday’s wave. Today’s suite has GFS/Euro ops skirting most precip south, Canadian half decent, and NAM/RRFS more mix/rain confining snows to northern PA. GFS/Euro ensembles look a little more amped on average vs their ops. I think most of us should see precip from this wave, my main concern is p-type issues.

Somebody in SE Mass is gonna end up with over 3 feet with that band sitting over them right now. Most reports around there are already nearly 2 feet.

I could be wrong but it sounds like everyone at work just wanted the extra day off, sound reasoning be darned. Which would make that really unfair for you to take that kind of flak. You certainly made a better forecast call than I did there. The other part of your post is a really good example of why I personally don’t do the YouTube/F-Book/Twitter Met stuff. I’d much rather discuss in a place like this forum where enough of the regulars (certainly not all haha) for the most part understand the difficulty in nailing this stuff down. Don’t ever be discouraged making your forecast calls in here.

Speaking of egos, I wonder how DT’s doing today haha. I mean yea DC wasn’t the epicenter, but let’s not forget where the Euro was with the coastal aspect of this thing as recently as like Friday.